Brown Pecans & Butter: In a skillet over medium heat, melt 3 tablespoons of unsalted butter, then add pecan halves, stirring until toasted and fragrant—about 3-5 minutes. Remove from heat and let cool.

Combine Dry Ingredients: In a medium bowl, whisk together 2 cups flour, 2 tablespoons cornstarch, 1 teaspoon salt, ½ teaspoon cinnamon, and 1 teaspoon baking soda. Set aside.

Combine Wet Ingredients: In a large bowl, mix cooled browned butter with 1 cup dark brown sugar and ¾ cup granulated sugar. Whisk in 1 tablespoon vanilla, 2 large eggs, and 1 yolk until smooth.

Mix Dough: Gradually add dry mixture to wet ingredients while mixing on low speed until just combined. Dough should be soft and slightly sticky.

Fold in Pecans: Carefully fold toasted pecans into the dough using a spatula. Ensure they are evenly distributed.

Chill Dough: Cover the bowl tightly with plastic wrap and refrigerate for at least 1 hour, up to 24 hours.

Bake Cookies: Preheat oven to 375°F (190°C). Line sheets with parchment. Scoop heaping tablespoons onto prepared sheets and bake for 9-12 minutes until edges are golden.

Cool Cookies: Let cookies cool on sheets for 5 minutes, then transfer to a wire rack to cool completely.